Transcatheter procedures are employed in increasing numbers for opening stenosed or occluded blood vessels in patients caused by deposits of plaque or other materials on the walls of the blood vessels. Such minimally invasive procedures have proven to be advantageous compared to traditional surgical procedures, such as open heart surgery. Stenosis in arteries and other blood vessels can be treated by permanently or temporarily introducing a stent into the stenosed region to open the lumen of the vessel.
However, embolic material may be released into the blood stream during implantation of a stent or another prosthetic device, placing the patient at great risk. Embolic material formed of calcium deposits, intimal debris, pieces of artheromatous plaque and/or thrombi has the potential of migrating downstream and causing distal tissue damage, for example stroke or myocardial infarction (see Topol, E. J. and Yadov, J. S., “Recognition of the Importance of Embolization in Athereosclerotic Vascular Disease”, Circulation 2000, 101:570). Embolic material which can potentially damage the distal tissue is often released during vascular intervention procedures, such as stenting of an artheromatous region.
To alleviate this problem, an embolic filter may be advanced to a site distal to the treatment site to filter and capture undesired embolic material from the blood. The filter is typically formed from a mesh material mounted on an expansion frame adapted to open from a contracted (or collapsed) configuration to a deployed (or open) configuration. The filter is typically inserted over or together with a guidewire using a delivery catheter. Following the treatment procedure, the filter is collapsed and removed from the body over the guidewire or together with the guidewire. Additional treatment devices, such as balloons and stents, can be inserted and removed via the same guidewire.
The filter should be positioned at a location as close as possible distal of the treatment site to ensure that most or all of the embolic debris is trapped by the filter. On the other hand, the guidewire should extend as far as possible into the body lumen to stabilize the treatment site. It is extremely difficult to achieve both these objectives simultaneously when using a built-in filter stop, because accurate placement of the stop relative to the treatment site by fluoroscopic observation is very difficult.
Therefore, there is a need for a guidewire stop capable of being stopped/locked on a bare guidewire, i.e. a guidewire section devoid of a preformed or fixedly attached stop. There is also a need for an intravascular treatment device capable of being stopped and/or locked on the guidewire at any user-selectable position following deployment of the treatment device in the body lumen.